The invention relates to molds, and more particularly to complete tooling packages for mold building structures.
The walls of a mold are formed around a plug. The mold replicates the contours of the plug in reverse. In the process of making mold structures to be used for manufacturing laminated fiberglass reinforced parts and thermoformed parts, tooling packages are developed to provide consistent appearance (surface profile) and dimensional control or stability in the finished parts. Tooling packages provided typically include various layers of laminated structure in an attempt to achieve this control.
One example of a conventional mold structure is shown in FIG. 1. The mold has a layer of gel coat 5, followed by barrier coat 10. There is a vinyl ester skin laminate 15 with a tooling resin layer 20 after it. There is a balsa wood core 25 followed by a second tooling resin layer 30.
However, present tooling packages can suffer from one or more problems. The balsa wood core can cause adhesion problems if the core is not applied at the proper time. The balsa is laid by hand which increases the time needed to make the mold. Some tooling resins have had problems with the fillers separating. In addition, excessive heat build-up can cause dimensional instability related to a dimensional change due to the exothermic reaction during the part making process. A minimum temperature of about 120° F. to about 130° F. is needed, with a temperature of about 120° F. to about 150° F. being desirable. However, desirably the temperature should not get above about 160° F. In addition, there can also be print-through of the glass fibers and/or balsa, or a surface that requires resurfacing.
All of these defects lead to additional processing time in providing a useful mold (tool) that can be used to provide good quality parts pulled from the mold. Moreover, conventional mold structures limit the useful life of the mold as it relates to the numbers of pulls.